Abstract: A circuit interruption apparatus, for an electrical network, comprising a circuit interruption device that is operatively connectable at a source side to a source of the electrical network and at a back side to a load of an electrical network. The circuit interruption device when closed permits and when open inhibits the current flow between the source side the back side. The current interruption device is configured to open when a current flowing therethrough meets or exceeds a fault current threshold. The circuit interruption apparatus also includes a fault current level determination unit that is configured to determine a predicted fault current level as a function of measured current and voltage values at the circuit interruption device before and after a variation in the current and voltage values at the circuit interruption device that result from a change of load at the back side of the circuit interruption device.

Abstract: An apparatus for determining a phase associated with a ground fault on a multi-phase power distribution network, the apparatus configured to, based on determination of a spike fault, determine which of a plurality of RMS values of phase-to-phase fault currents is the minimum, said minimum RMS value indicative of a particular phase of the multi-phase power distribution network associated with the ground fault.

Abstract: A DC distance protection scheme for protecting a DC power transmission medium within the DC electrical power network. The DC distance protection scheme includes a protection device that is coupled in use to a DC power transmission medium. The protection device is operable to protect the DC power transmission medium from an electrical fault. The DC distance protection scheme also includes a measurement apparatus to selectively measure the current and voltage of the DC power transmission medium. In addition the DC distance protection scheme also includes a controller that is programmed to calculate an operating voltage of the DC power transmission medium using the measured current and voltage; perform a transient comparison between the calculated operating voltage and the measured voltage; and operate the protection device to protect the DC power transmission medium if the transient comparison meets a predefined criterion.

Abstract: A DC protection scheme for protecting a DC power transmission medium within a DC electrical power network. The scheme includes a protection device coupled to a DC power transmission medium, being operable to protect the power transmission medium from a fault; an apparatus to measure at least one electrical property of the power transmission medium; and a controller programmed to determine the direction of the electrical fault; determine whether the electrical fault is an internal or external fault; and operate the protection device to protect the DC power transmission medium if the determination of the direction of the electrical fault and/or the determination of whether the electrical fault is an internal or external fault meet a predefined criterion.

Abstract: In differential protection schemes for electrical power systems there is a need to employ a synchronization technique to enable time alignment of local terminal current with received current from a remote terminal in order reliably to operate the differential protection scheme. A method of determining a communication time delay in a communication network between a local terminal and each of a plurality of remote terminals in a multi-terminal multi junction electrical power system includes: (a) calculating a respective initial communication time delay between each remote terminal and the local terminal; (b) calculating a respective junction time delay between respective first, second and third pairs of adjacent junctions; and (c) correcting the calculated initial communication time delay of each remote terminal spaced from the local terminal by two or more junctions according to each corresponding junction time delay arising between the or each said remote terminal and the local terminal.

Abstract: In the field of multi-terminal electrical power network protection, a protection apparatus comprises a measurement apparatus to measure the respective terminal current (IL, IR1, IR2, IR3, IR4, IR5) flowing at each terminal (L, R1, R2, R3, R4, R5) in a multi-terminal network that includes a plurality of electrically interconnected terminals (L, R1, R2, R3, R4, R5). The protection apparatus also includes a control unit that is programmed to process the measured terminal currents (IL, IR1, IR2, IR3, IR4, IR5) to obtain first and second summed values (IPOS(n), INEG(n)).

Abstract: An apparatus for determining a measure of the frequency of an electrical signal is provided. The apparatus is configured to, based on a plurality of samples of the electrical signal, determine a Hilbert transformation to obtain a value for each of the samples of the electrical signal for use as an imaginary representation of each of the samples of the electrical signal and combine each said imaginary representation with a corresponding real representation of the samples of the electrical signal to form a complex representation of the electrical signal; perform a Fourier transform on each said complex representation of the samples of the electrical signal and determine a phase angle therefrom; and determine a measure of the frequency of the electrical signal based on a derivative of the phase angle with respect to time.

Abstract: Embodiments of the disclosure relate to systems and methods of locating a fault in a multi-terminal power transmission scheme. According to at least embodiment of the disclosure there is provided a method of locating a fault in a multi-terminal electrical power transmission scheme in which each terminal is connected with a junction via a power transmission section and the or each junction interconnects a plurality of power transmission sections.

Abstract: A dynamic line rating determination apparatus configured to control the current applied to a power line conductor by determining a dynamic maximum current rating for said power line conductor, based on measured voltage and current phase vectors taken at two temporally spaced sample times, the phase vectors including a voltage and current phase vector for each phase of electrical power carried by the power line conductor at a first and second end of the power line conductor; and determining the dynamic maximum current rating by; applying the phase vectors to a power line model to estimate the conductor temperature, applying the estimate to a thermal model to predict a steady state temperature that the power line conductor will reach, and calculate the dynamic maximum current rating based on the prediction of the steady state temperature, a power line conductor current, and a maximum temperature limitation value.

Abstract: There is provided a protection apparatus for protecting an electrical network. The protection apparatus comprises: at least one protection device configured to protect the electrical network from a fault in response to a or a respective protection criterion being met; and a controller configured to: receive real-time information on a change in topological structure of the electrical network; perform an online determination of the real-time impedance or admittance matrix of the electrical network based on the change in topological structure of the electrical network; and adapt the or each protection criterion based on the real-time impedance or admittance matrix.

Abstract: In the field of Rogowski coils for the measurement of current within a conductor there is provided an electrical interface for connection to a Rogowski coil arranged around a primary conductor. The electrical interface includes an input that is configured to sample an input voltage signal from the Rogowski coil. The electrical interface also has an integrator circuit which includes an integrator module that is configured to integrate the sampled input voltage signal to provide an output voltage signal from which can be derived a primary current flowing through the primary conductor. The integrator module employs a transfer function that includes an attenuation factor.

Abstract: In the field of fault location within a power transmission network, a method of determining a fault location in a power transmission conduit includes: (a) sampling at an original sampling frequency a signal propagating through the power transmission conduit to establish a first data set including a plurality of sampled signal characteristics; (b) interpolating the first data set to establish a second data set including an increased number of signal characteristics whereby the second data set has an equivalent sampling frequency higher than the original sampling frequency; (c) identifying a fault wave signal within the second data set; and (d) utilising the propagation characteristics of the fault wave signal to determine the origin of the fault wave signal within the power transmission conduit.

Abstract: An apparatus for determining a phase associated with a ground fault on a multi-phase power distribution network, the apparatus configured to, based on determination of a spike fault, determine which of a plurality of RMS values of phase-to-phase fault currents is the minimum, said minimum RMS value indicative of a particular phase of the multi-phase power distribution network associated with the ground fault.

Abstract: There is provided a method of locating a fault in a power transmission scheme. The power transmission scheme includes power transmission sections and a first end connection point, a second end connection point, and at least one intermediate connection point. The method includes (i) measuring first and second end voltage phasors at the first and second end connection points respectively; (ii) obtaining a first set of voltage phasors, which includes the measured first end voltage phasor and includes respective voltage phasors at each of the second and intermediate connection points; (iii) obtaining a second set of voltage phasors, which includes the measured second end voltage phasor and includes respective voltage phasors at each of the first and intermediate connection points; (iv) comparing the first and second sets of voltage phasors to identify the power transmission section or connection point corresponding to the location of the fault.

Abstract: In the field of power system stability there is provided a method of predicting the presence of an out-of-step condition in a power system that includes a plurality of generators, the method including the steps of: (a) obtaining a differential value (?COIk) between a rotor angle (?k) of an individual one of the plurality of generators and an equivalent rotor angle (?COIk) of the centre of inertia of the remainder of the plurality of generators; (b) processing the differential value (?COIk) to determine whether the differential value (?COIk) is predicted to reach a predefined reference threshold (?threshold); and (c) predicting the presence of the out-of-step condition in the power system if the differential value (?COIk) is predicted to reach the predefined reference threshold (?threshold).

Abstract: A DC protection scheme for protecting a DC power transmission medium within a DC electrical power network. The scheme includes a protection device coupled to a DC power transmission medium, being operable to protect the power transmission medium from a fault; an apparatus to measure at least one electrical property of the power transmission medium; and a controller programmed to determine the direction of the electrical fault; determine whether the electrical fault is an internal or external fault; and operate the protection device to protect the DC power transmission medium if the determination of the direction of the electrical fault and/or the determination of whether the electrical fault is an internal or external fault meet a predefined criterion.

Abstract: A DC distance protection controller for identifying a fault within a protection zone that extends between a first terminal and a set point along a DC power transmission conduit which lies between the first terminal and a second terminal within a DC electrical power network. The protection controller periodically obtains as respective sampled pairs a measured voltage value and a measured current value of the DC power transmission conduit; isolates a fault component voltage value and a fault component current value to define a respective corresponding isolated pair; calculates from each isolated pair a fault component operating voltage of the DC power transmission conduit at the set point; compare a given calculated fault component operating voltage with a historical voltage value; and identifies a fault within the protection zone when the given calculated fault component operating voltage is greater than the historical voltage value.

Abstract: A DC distance protection scheme for protecting a DC power transmission medium within the DC electrical power network. The DC distance protection scheme includes a protection device that is coupled in use to a DC power transmission medium. The protection device is operable to protect the DC power transmission medium from an electrical fault. The DC distance protection scheme also includes a measurement apparatus to selectively measure the current and voltage of the DC power transmission medium. In addition the DC distance protection scheme also includes a controller that is programmed to calculate an operating voltage of the DC power transmission medium using the measured current and voltage; perform a transient comparison between the calculated operating voltage and the measured voltage; and operate the protection device to protect the DC power transmission medium if the transient comparison meets a predefined criterion.

Abstract: A method of protecting a power transformer including: monitoring an external fault indication signal; carrying out locally a fault determination; carrying out locally an inrush current determination; and issuing a final trip signal to protect the power transformer if the external fault indication signal identifies that a fault has occurred and the locally carried out fault determination confirms that a fault has occurred; or the external fault indication signal identifies that a fault has occurred and the locally carried out fault determination identifies that no fault has occurred but after a predetermined delay the locally carried out inrush current determination confirms the absence of an inrush current.

Abstract: An apparatus for determining a fault location distance or distance protection in a multi-phase power transmission medium, configured to; determine a set of line fault parameters based on a measurement of voltage and current at a point of said power transmission medium and a fault type, the line fault parameters determined at a plurality of sample times determine a derivative with respect to time of a line fault parameters representative of an inductive part of measured faulty phase current; determine a set of phasors using a Fourier transformation of the derivative and of the remaining line fault parameters at the plurality of sample times and use said set of phasors to determine a fault location distance or distance projection distance along the power transmission medium; wherein, the determination of the fault location distance or the distance protection distance is based on the line equation; U . P = U . F + [ R 1 ? I . PR + X 1 ? 0 ? I . PX ] ? D F .